Microwave tube cooling assembly

ABSTRACT

The invention relates to a connecting flange for a microwave tube arranged in an external resonator space, the connecting flange having two tubular pieces for the inlet and the outlet of the cooling air. The air enters the resonator space in oblique direction, flows around the microwave tube along an approximately Alpha -shaped path, and emerges from the other slanting tubular piece. Axial metal plates in the tubular pieces form an extremely low resistance to the flow of cooling air while exhibiting very high damping for the resonator waves.

Unite States Patent Inventor Appl. No.

Filed Patented Assignee Priority Friedrich Potzl Hamburg, Germany 803,256

Feb. 28, 1969 May 25, 1971 U.S. Philips Corporation New York, N.Y.

Mar. 8, 1968 Germany MICROWAVE TUBE COOLING ASSEMBLY 7 Claims, 12 Drawing Figs.

U.S. Cl 333/83, 333/98, 313/36 llnt. Cl 1101p l/16, HOlp 7/06 Field of Search 313/17,22,

[56] References Cited UNITED STATES PATENTS 2,467,230 4/1949 Revercomb et al 2,732,473 1/1956 Ellsworth 2,868,939 1/1959 Pound 3,050,606 8/1962 Tibbs Primary Examiner-Herman Karl Saalbach Assistant Examiner-Marvin N ussbaum Attorney-Frank R. Trifari ABSTRACT: The invention relates to a connecting flange for a microwave tube arranged in an external resonator space, the connecting flange having two tubular pieces for the inlet and the outlet of the cooling air.

The air enters the resonator space in oblique direction, flows around the microwave tube along an approximately ashaped path, and emerges from the other slanting tubular piece. Axial metal plates in the tubular pieces form an ex tremely low resistance to the flow of cooling air while exhibiting very high damping for the resonator waves.

Pmmmmmsn 3,581,251

SHEET 1 BF 3 IN VENTOR. FRIEDRICH POTZL Z- AGENT PATENTEnuAYzsisn 358L251 SHEET 2 BF 3 INVENTOR FRIEDRICH PO'ITZL AM x AGENT PATENTED HAYZS I97! SHEET 3 [IF 3 INVENTOR FRIEDRICH PO'TZL BY w AGENT MICROWAVE TUBE COOLING ASSEMBLY The invention relates to a connecting flange for a microwave tube arranged in an external resonator space, said connecting flange having two tubular pieces for the inlet and the outlet of the cooling air, respectively, while the openings of the tubular pieces are prepared to have a high damping for the microwaves of the resonator space.

Hitherto tubular pieces have been employed, which are fastened at right angles to a flange, while the flanges are arranged side by side opposite each other in the resonator wall. In order to avoid loss of high frequency energy from the resonator space through the openings of the tubular pieces, these openings have been covered by copper gauze or a perforated copper plate.

However, these known embodiments have the disadvantage that the air stream passed radially in the resonator space strikes the tube wall to be cooled at right angles so that strong whirling is produced. When the flanges are arranged side by side, the disadvantage is involved that a large portion of the air stream flows directly towards the outlet piece. Moreover, the resistance to theair stream is high owing to the gauze or the perforated plate.

The invention has for its object to mitigate said disadvantages as far as possible. For this purpose the two tubular pieces for the inlet and the outlet of cooling air of a metal connecting flange for cooling a tube arranged in an external resonator space, the cooling air openings being provided with a damping member for the resonator waves, are arranged side by side at opposite angles to the axis of symmetry of the flange on said flange so that the air stream follows an approximately a-shaped path around the tube to be cooled, while the tubular pieces are provided with axial metal plates providing high damping of the microwaves of the resonator, but forming a low resistance to the stream of cooling air.

The invention is based on the phenomenon described in Philips Technisch Tijdschrift annum 23, 1961/62, page I96 that microwaves are subjected to strong damping in rectangular hollow wave-pipes, if their frequency lies below the socalled limit frequency. By dividing the openings of the tubular pieces by the axial metal plates into a number of sufficiently narrow waveguides, so that the limit frequency of each waveguide exceeds the highest resonator frequency, a great damping for the resonator frequency is obtained. The coolingair tubes can therefore not give rise to high losses of high frequency energy.

The slanting position of the tubular pieces is very conductive to guide the coolant, for example, cooling air. The air enters the resonator space in oblique direction, flows around the microwave tube along an approximately a-shaped path and emerges from the other slanting tubular piece. The axial metal plates in these tubular pieces form an extremely low resistance to the flow of cooling air. On the other hand these metal plates together and with the inner walls of the tubes form hollow waveguide compartments for the frequencies lying in the microwave range, which compartments exhibit very high damping for the resonator waves. In order to further improve such a waveguide damping, the plates according to the invention may have a particular shape inside the tubular pieces. According to the invention the plates may be arranged in the form of a star or at right angles to each other, for example, so that they form a grating. One or more plates may furthermore be cylindrical. In a preferred embodiment a cylindrical plate may be arranged coaxially in a tubular piece, while it is provided on the outer side with radial plates extending axially at right angles to the other wall up to the inner wall of the tubular piece. According to the invention some of the radial plates may be extended inside the cylindrical plate up to the axis of the tubular piece.

Consequently, the total sectional area of a tubular piece is divided by the plates according to the invention into a plurality of tubular passages of small diameters, while the individual sectional areas of the passages have substantially the same dimensions. The number of such plates must, ofcourse, not be too great, since otherwise the resistance to the flow would become appreciable. On the other hand the number may be adapted with sufficient accuracy to the highest microwave frequency at which a predetermined minimum damping must still be obtained.

The connection of the plates with the inner wall of the tube, that is to say the electrical connection, may be established by means of soft solder or a welding joint or by the natural elasticity of the metal plates when suitably shaped. The elasticity has, of course, to be such that the plates cannot be carried along by the air stream. As the case may be, a mechanical anchoring has to be provided. For this purpose the tubular pieces may have a tapering inner wall so that the insert has also to be tapering and thus cannot be carried along in the direction of flow of the air.

When the circular sectional area is divided into a number of parallel passages, it is important for obtaining a high ratio between damping and flow resistance that the separate passages into which the sectional area of the tube is divided by thin plates, should have a sectional area of a length approximately equal to the width measured at right angles thereto. Therefore, a square sectional area of the passages is most favorable.

The invention will be described more fully with reference to the drawing, which shows a few embodiments.

FIG. 1 is partly a side elevation and partly a sectional view of a metal connecting flange for cooling air having two tubular pieces secured thereto.

FIG. 2 is a plan view of the device of FIG. I, viewed from the inner side of the external resonator.

. FIG. 3 shows a metal insert having axial plates in accordance with the invention.

FIGS. 4 to 12 show various forms of metal inserts of the tubular pieces in accordance with the invention.

Referring to FIG. 1, reference numeral 1 designates the metal connecting flange which partly covers the opening concerned in the wall of the external resonator. The flange is provided with two tubular pieces also of a metal, the axes of which are slightly slanting towards each other and at opposite angles to the axis normal to the head face of the flange. These two tubular pieces are designated by 2 and 3 in FIG. 1. Through one tubular piece 2 the air is passed in the direction of the arrow 4 by pressure into the external resonator; it flows around the microwave tube 5 and emerges from the resonator space in the direction of the arrow 6 through the tubular piece 3. Since the two tubular pieces 2 and 3 are arranged side, by side and in relatively slanting positions, the air stream can follow a substantially a-shaped path around the, for example, horizontal microwave tube 5, while it can flow, in addition, upwards and downwards along the tube. Normally the two tubular pieces 2 and 3 are arranged one above or one below the other, the cooling air entering, for example, through the lower piece.

FIG. 2 is an elevation of the device of FIG. I, in which the position of the metal inserts 7 in the tubular pieces 2 and 3 is clearly shown.

FIG. 3 shows a substantially star-shaped metal insert of axially extending plates, which may be connected with the inner walls of the tubular pieces 2 and 3 in various ways as shown in FIGS. 4 and 5; by means of soft solder as shown in FIGS. 4 to 8 and by simply bending over the ends of the plates arranged in a star shape as shown in FIGS. 5 to Q. The insert of FIG. 5 can therefore always by drawn out.

In this way the tube damping determined by the largest dimension d of the cross-sectional area is combined with minimum flow resistance. In a star-shaped division of the sectional area of the tube (FIG. 6) a division by 6 (d=D/2) is the optimum whereas a division by 8 (FIG. 7) with d=Dl2 or a division by 4 with d=O.7D are still permissible, while further divisions provide only narrower sectors with higher flow resistances, the longest dimension remaining, however d=D/2 (FIG. 9). With a stabshaped division the length of a separate sector is equal to the radial dimension, whereas the width of the separate sector corresponds to the length of the sector chord.

FIG. shows a device having orthogonal plates forming a grating.

FIG. 11 shows a device comprising a cylindrical plate arranged coaxially in a tubular piece and provided at its surface with radial plate at right angles to said surfaces. These plates have their larger dimensions in the axial direction. A further variant of this device is shown in FIG. 12.

All inserts may be formed by relatively fitting plates, or plates solderable to each other as is most appropriate for the purpose aimed at when the inner walls of the tubular pieces have a tapering shape, especially the tubular piece for the inlet of the cooling air, the metal insert or the plates interconnected in various ways maybe bevelled so that the plates fit accurately and no further fastening means are required for preventing shift of the plates by the air stream. Since this shape is quite simple, it is not shown in the drawing. The inlet piece will taper inwardly and the outlet piece will taper outwardly, viewed from the resonator space.

Iclaim:

1. An assembly for use with a supply of cooling air to cool a microwave tube, comprising a housing with a resonant cavity in which the microwave tube isdisposed, and connected to a wall of the housing, inlet and outlet conduits through which cooling air is supplied, directed to flow about said microwave tube in the cavity, and subsequently discharged, the conduits being disposed adjacently and oriented at a mutually oblique angle whereby the air may flow about a loop-shaped path in the cavity around the microwave tube, and a damping member formed of axially extending plates disposed within at least one of said conduits and defining a plurality of passages providing high damping of resonator microwaves but a low resistance to the air stream.

2. An assembly according to claim 1 wherein the limit frequency of each conduit exceeds the highest resonator frequency.

3. An assembly according to claim 2 wherein the plates in end view extend from the center generally radially outward toward the conduit walls and form a star.

4. An assembly according to claim 2 wherein the plates'in end view define right angles between each other and form rectangular spaces.

5. An assembly according to claim 2 wherein at least one of the plates in end view defines a curved cylinder.

6. An assembly according to claim 5 wherein at least one plate formed as a cylinder is coaxially disposed within at least one of said conduits, the cylinder provided on its outer periphery with plates extending radially to the inner walls of the conduit.

7. An assembly according to claim 2 wherein the plates of the damping member are arranged to define in end view substantially equal sectional areas for air passages. 

1. An assembly for use with a supply of cooling air to cool a microwave tube, comprising a housing with a resonant cavity in which the microwave tube is disposed, and connected to a wall of the housing, inlet and outlet conduits through which cooling air is supplied, directed to flow about said microwave tube in the cavity, and subsequently discharged, the conduits being disposed adjacently and oriented at a mutually oblique angle whereby the air may flow about a loop-shaped path in the cavity around the microwave tube, and a damping member formed of axially extending plates disposed within at least one of said conduits and defining a plurality of passages providing high damping of resonator microwaves but a low resistance to the air stream.
 2. An assembly according to claim 1 wherein the limit frequency of each conduit exceeds the highest resonator frequency.
 3. An assembly according to claim 2 wherein the plates in end view extend from the center generally radially outward toward the conduit walls and form a star.
 4. An assembly according to claim 2 wherein the plates in end view define right angles between each other and form rectangular spaces.
 5. An assembly according to claim 2 wherein at least one of the plates in end view defines a curved cylinder.
 6. An assembly accorDing to claim 5 wherein at least one plate formed as a cylinder is coaxially disposed within at least one of said conduits, the cylinder provided on its outer periphery with plates extending radially to the inner walls of the conduit.
 7. An assembly according to claim 2 wherein the plates of the damping member are arranged to define in end view substantially equal sectional areas for air passages. 